local calendars inaccessible after upgrade from natty (workaround included)

[Fionn]

Upgrading Evolution from 2.3x (natty) to 3.2 (oneiric), seemingly came with a lot of changes of internal data storage formats.

Unfortunately the conversion process leaves room for improvement.

After the upgrade, calendar kept crashing on me often and randomly. Also, I could not accept new meeting requests. Instead, evolution showed the following error message:
Could not load calendar >XYZ< (No backend factory for 'file' of 'VEVENT')

Also, the mentioned calendar can neither be opened nor deleted.

According to this source:
https://bugzilla.redhat.com/show_bug.cgi?format=multiple&id=716448

It helps to edit some rather complicated xml values in gconf-editor which apparenty became flawed during the upgrade.

In my case, fixing the base_uri helped somewhat; the above mentioned error message was replaced by a different one, for which I'll probably open another bug after some closer examination.

Anyway, it may be worth checking whether this is the only case of a malformed base_uri and if the upgrade process could be changed to double-check for them.